Planting Grass Seed in the Summer

Not all grass varieties are suited for planting during the hot, humid summer months. However, it is possible to grow some types of grasses successfully in summer, they'll just need some extra care. Here's how to set yourself up for success.

When's the Best Time to Plant?

The best time to plant depends on where you live and the type of grass you're planting. If you live in the North and are planting cool-season grass varieties, like Kentucky bluegrass, perennial ryegrass, or fescues, the best time to plant grass seed is the spring and again in the fall. Cool-season grasses grow most actively when the air temperatures are between 50 and 80 degrees F, the soil temperature is 50 to 65 degree F, and rain is plentiful. Cool-season grasses go dormant and do not grow during hot weather, when the soil temperature goes above 65 degrees F. Since this is common during the peak summer months, planting cool-season grass seed can result in poor seed germination or even seedling death.

On the other hand, if you live in the South and are planting warm-season grass varieties, like centipedegrass, zoysiagrass, bahiagrass, or bermudagrass, the best time to seed is late spring through mid-summer. Warm-season grasses are originally from tropical areas of the world and, once established, are able to thrive in scorching sun and high temperatures. They grow most actively when air temperatures are warm, between 70 and 90 degrees F. In addition, seeds need warmer soil temperatures than cool-season grasses to germinate (ideally between 65 and 70 degrees F).

Planting in the Heat

If you live in the South and decide to plant a warm-season grass in the heat of summer, or if you have young grass seedlings still trying to become established when the weather turns hot, try these tips for success.

1. Use high-quality grass seed

Choose a Scotts® Turf Builder® Grass Seed that is right for your location. Also, be sure to take into consideration the growing conditions of your area: How much wear and tear will the lawn get from children and the family pet? How much sun? Is the soil sandy?

• Bermudagrass tolerates a very low mowing height and is great for areas challenged by scorching heat and drought.

• Centipedegrass grows best in sunny, warm, humid areas of the South with sandy, acidic soil, and does not need a lot of fertilizer.

• Zoysiagrass is most common in the middle part of the U.S. It is the most cold-tolerant of all the warm-season grasses but is very slow growing and may require more than a year to become established.

• Bahiagrass has excellent heat and drought tolerance and is ideal for Deep South coastal regions because it grows well in sandy, acidic soils. Pensacola bahiagrass has a finer leaf texture and is more cold tolerant, while Argentine bahiagrass is darker green and has wider leaf blades.

If you need help finding a grass type that is right for your lawn, visit your local garden center or check out our Identify Your Grass article for more information.

2. Be meticulous about watering

If you want a thick, green lawn later, how you water your new lawn plays a very important role. Once your grass seed is planted, the top inch of soil should be kept consistently moist but not soggy for the first 2 to 3 weeks. This means misting the seeded area with water daily, or more if needed. If the weather is hot and dry, you will need to mist more frequently. After your grass seed has sprouted, keep the top 2 inches of soil moist, but allow it to dry slightly between waterings. This will encourage the grass roots to start growing deep in the soil. As your grass seedlings continue to grow, continue to reduce the watering to every 2 to 3 days. However, if the temperatures are high, don't allow the soil to dry out. (Young grass seedlings at this stage are still susceptible to drying out.) Once your new lawn reaches a mowing height, cut back watering to once or twice a week. The first 6 to 8 inches of soil should be moist but allowed to dry out before watering again. This will continue to encourage the grass roots to grow deeper in the soil.

3. Watch out for hot days with heavy rain

If the extended weather forecast is calling for extremely hot temperatures, high humidity, and lots of rain, it's a good idea to hold off on planting grass seed. High temperatures combined with waterlogged soils create conditions in which there is no soil oxygen for roots to breathe. If that happens, they cannot absorb nutrients and water, and they may die. If you've ever driven by a farmer's field, you can see the effects of waterlogged soils on young soybean and corn plants. Parts of the field that are saturated with water will have plants that are yellow and stunted. The same high temperatures and soil aeration stresses that stunt those robust farm crops can kill tiny grass seedlings.

4. Know that hot, sticky nights can lead to grass disease

High nighttime temperatures above 65 degrees F, combined with excess moisture and humidity, are particularly stressful for young grass seedlings. Lawn fungal diseases such as damping off (Pythium) and brown patch (Rhizoctonia) become very active under these conditions. They can attack and possibly kill young grass seedlings. To help prevent these problems, make sure the planting area is well-drained before seeding and always follow the seeding rate on the back of the bag. (Too many seedlings trying to grow in the same space reduces air circulation, prevents water from properly evaporating, and can lead to disease problems.

Warm temperatures, combined with water-logged soils, create conditions where there is no soil oxygen for roots to breathe. If the roots can't breathe, they cannot absorb nutrients and water and they may die. As an example, you can see the stress of water-logged or saturated soils in many farm fields of young soybeans and corn that appear yellow and stunted. The same heat, humidity and soil aeration stresses that stunt those robust farm crops can kill tiny grass seedlings. So hold off on planting grass seed during times of severe heat, humidity, and excess water stress.